Medical institutions are equipped with a radiographic apparatus configured to emit radiation to image a subject M. Such a radiographic apparatus includes a radiation source 53 and a detector 54 as illustrated in FIG. 14. The radiation source 53 emits radiation, and the detector 54 detects radiation. A top board 52 is provided between the radiation source 53 and the detector 54. The top board 52 supports the subject M placed thereon. See, for example, Japanese Patent Publication No. 2010-012101A.
Such a radiographic apparatus allows inclination of the top board 52. The top board 52 rotates around an axis C, whereby the subject M on the top board 52 is inclinable to a desired angle. See FIG. 15.
The top board 52 is rotated, and the radiation source 53 and the detector 54 rotate following the rotation with a maintained positional relationship to the top board 52. Consequently, the rotation of the top board 52 never changes the positional relationship among the subject M, the radiation source 53, and the detector 54. Such rotation achieves imaging while a direction where a liquid contrast medium administered into the subject M drips is adjusted.
Here, the radiation source 53 and the detector 54 are movable relative to the top board 52 in a long-side direction of the top board 52. In the currently-used apparatus, a positional relationship between the top board 52 and the center of the rotation is constant even when the above movement is made. This is because a positional relationship between the top board 52 and a rotating mechanism rotatably holding the top board 52 is constant regardless of the movement of the radiation source 53 and the detector 54.    Patent Literature 1: Japanese Patent Publication No. 2010-012101A